Automatic air-pump.



G. W. DOPKINS.

AUTOMATIC AIR PUMP.

APPLICATION FILED FEB. 12. I9l6.

LQQLW5W Patented Apr. 3,1917.

2 SHEETSSHEET l.

Inventor Attorneys a. w. DOPKINS.

AUTOMATIC AIR PU'MP.

APPLICATION FILED FEB. 12, 1916.

Patented Apr. 3, 1917.

2 SHEETS-SHEET 2.

Attorneys .lowing is a specification.

e r W W AUTOMATIC AIR-PUMP.

Specification of Letters Patent.

Patented Apr. 3, 1917.

Application filed February 12, 1916. Serial No. 77,943.

To all whom it may concern."

Be it knownthat I, GEORGE W. DorKrNs, a citizen of the United States, residing at Morris, in the county of Stevens and State of Minnesota, have invented a new and useful Automatic Air-Pump, of which the fol- The present invention appertains to pumps, and aims to provide a novel and improved air pump adapted especially for use upon automobiles, although useful for other purposes as well, and having a mechanism whereby the pump is automatically connected to a driving member when the pressure created by the pump is decreased, for disconnecting the pump from the driving. member when the pressure created by the pump increases to a predetermined amount.

The present pump is adapted to be operated by the engine of the automobile for supplying compressed air into a compressed air tank, the compressed air being used for operating a pneumatic engine starter, for inflating the tires, operating a pneumatic signal, or the like. With the present pump, the pressure within the tank is maintained practically uniform, so as to avoid an excessive or insuflicient pressure as long as the engine is in operation.

The present pump embodies an automatic controlling mechanism having novel and improved features of construction, to enhance the utility and efliciency thereof, and the en-- tire construction being comparatively simple and compact.

With the foregoing and other objects in view which will appear as the description proceeds, the invention resides in the combination and arrangement of parts and in the details of construction hereinafter described and claimed, it being understood that changes in the precise embodiment of the invention herein disclosed ean be made within the scope of what is claimed without departing from the spirit of the invention.

The invention is illustrated in the accompanying drawings, wherein Figure 1 is a mediumsection of the pump, portions being shown in elevation.

Fig. 2 is a sectional detail taken on the 1ine-2-2 of Fig. 3. 4

Fig. 3 is'a sectional detail taken on the line 3 3 of Fig. 1.

In carrying out the invention," there is provided a crank case 1 forming the base of the pump, and upon which is secured a body 2 having a cylinder 3 and a pair of pump cylinders 4, the cylinders being parallel and cast en bloc. The ends of the cylinders remote from the case 1 are closed by a head 5 bolted or otherwise attached 'to the body 2.

In order to supply air from the atmosphere to the pump cylinders 4, the body 2 is provided between said cylinders with an air inlet port or opening 6, and has a pair of passages 7 diverging from the opening 6 and extending into the head 5. These passages 7 have valve seats '8 upon which ball valves 9 are seatable, to provide check valves which permit the air to flow inwardly but not outwardly. The valves 9 are normally seated by expansion springs 10 disposed between the valves and the upper ends of the passages 7, and the head 5 has ports or passages 11 extending from the upper portions of the passages 7 to the upper ends of the cylinders 4 to communicate therewith. Air can thus be sucked into the cylinders byway of the opening 6, passages 7 and ports 11.

In order to conduct the compressed air from the cylinders 4, the head 5 is provided above each cylinder with a passage or bore 12 communicating with the cylinder. The bores 12 have valve seats 13 upon which are seatable ball valves 14, forming check valves which permit the air to be forced through the bores 12 from the cylinders 4, and which prevent the return flow of the air. The outer ends of the bores 12 are closed by removable screw plugs 15, and coiled expansion springs 16 are disposed between the valves 14 and plugs 15 for seating said valves. The head 5has a longitudinal bore or passage'l'? intersecting the bores 12 to communicate therewith, and the bore 17 has a branch 18 between the bores 12 and communicating with an air passage 19 with which therbody 2 is provided between the cylinders 4,'and which is adapted to commu'nicate with'tlie compressed air tank (not i the case 1. The crank shaft 26 is journaled between the cranks 24-25 to a pedestal or bearing 27 carriedby the case 1, and one 1 terminal of the crank shaft 26 is j ournaled within a sleeve 28 mounted for rbtation within a bearing29 with which the respective end of the case 1 is formed. Attached I to the outer end of the sleeve 28 is a sprocket wheel 30 which can be connected by a sprocket chain to the crank shaft of the engine (not shown), although said sleeve 28 J can be connected to the engine or prime mover in any other suitable manner.

' lubricant splasher 31 is carried by the sleeve 28 Within the casing 1' for splashing lubricant contained within said case to lubricate the pistons and other Working parts, and

the inner end of the sleeve 28 is provided with a toothed clutch portion 32. During the operation of the engine, the sleeve 28, which is the driving member, isoperated continually, and is connected to the crank shaft 26 of the pump, by means of a clutch collar 33 feathered or splined imon the crank shaft and having teeth at one end to engage the clutch portion 32'. The collar has an annular groove 34 in order that it can be shifted, as will hereinafter more fully appear. The clutch collar 33 is shifted by means of'a piston 35 slidable within the cylinder 3 and having suitable packing rings, said piston 35 having apiston rod 36 projecting into the case 1 and sliding 1 through an inwardly projecting bracket" 37 dling the 'clutch collar 33, andprovided at its ends with rollers or other elements 44 engaging within the groove 34, in order that when the bell crank lever is oscillated,

the collar 33 is shiftedlongitudinally upon thecrank shaft either toward or away from the sleeve 28. The bell crank lever 41 is oscillated bythe reciprocation of the piston'35, and when the piston 35 is moved I upwardly under the influence of the spring 38, the arm of the bell crank lever is swung upwardly, and this moves the fork '43 toward the sleeve 28, so that the clutch .member or sleeve 28.

collar 33 is shifted into engagement with sald sleeve, causing the clutch collar 33 and crank shaft 26,to rotate with the driving The piston rod 36 is provided with stop lugs 45 above and below the bracket 37, and

adapted to' contact with said bracket for limiting the reciprocat ory movement of the piston 35. The bracket 37 ,has a 1ongitudinal bore 46 opening through the side wall of the case 1, and a detent pin 47 is slidable within the inner end of the bore 46 and has a pointed end engageable in the V shaped notches 48 and 49 with which the piston rod 36 is provided between the lugs 45. The pin 47 is pressed toward the piston rod 36 by means of a coiled wire expansion spring 51 disposed within the bore 46 between the pin 47 and an adjusting screw threaded within the bore. Saidscrew 50 can be rotated, when the plug52 is removed from the 'outer end of the bore 46, a screw driver or other suitable implement being employed for this'purpose. The tension of the spring 51 can therefore beregulated, whereby it will require more or less pressure to dis engage the pin 47 from one of the notches 48-49.

In operation, supposing the pressure of the air beyond the valves 14 is such as is normally desired, the pressure will extend into the cylinder 3 by way of the bore 17 and its branch 20, and will overcome the tension of the spring38, so that the piston 35 will be forced downwardly, which will swing the bell crank lever 41 in such a direc-.

tion as to shift the clutch collar 33 away from the sleeve 28. The sleeve 28 will therefore rotate idly, and the detent pin 47 will snap into engagement with the notch 48, for preventing the vibration of the piston 35,

and to hold said piston in lowered position until the pressure is reduced sufliciently to bring the spring 38 into action. When the pressure lowers below a certain amount, the pressure above the piston 34- is decreased, and the spring 38 then overcomes the air pressure, and raises the piston 35, it being necessary for the air pressure to be reduced sufliciently to enable the spring 38 to force the detent pin 47 out of the notch 48. The piston 35 is" therefore raised, which will swing the bell crank lever 41in such a direction as to shift the clutch collar 33 toward and into engagement with the sleeve 28, the pin 47 .now engaging the notch 49 to hold the piston 35 raised. The crankshaft 26 will therefore be rotated with the sleeve 28,

operating the pistons 22, and forcing compressed air out of the cylinders 4 into the tank (not shown). The pin 47 in engaging.

the notch 49, will hold the piston 35 raised until the pressure of the air becomes sufficient to overcome the holding tendency of the pin 47, in which event the piston 35 will be depressed. quickly. The detent pin 47 this holds the piston 35 in either position until a predetermined high or low pressure occurs, in which event the pin 47 is moved out of engagement from the respective notch. The present pump is entirely automatic, being automatically connected with and disconnected from the driving member as the pressure lowers and increases, whereby a practically uniform pressure of air within the tank is provided.

Having thus described the invention, what is claimed as new is:

An air pump having a crank case and a body attached thereto, said body being provided with a pump cylinder and another cylinder parallel therewith, the second mentioned cylinder communicating at its outer end with the outlet of the pump cylinder, a crank shaft mounted for rotation within the crank case, a piston working in the pump cylinder and connected to the crank shaft, a bracket at the inner end of the second mentioned cylinder, a piston working within the second mentioned cylinder andhaving a piston rod slidable through said bracket, an expansion spring between said bracket and second mentioned piston, a driving sleeve journaled in one wall of the crank case and having a clutch portion at its inner end, the crank shaft being journaled within said sleeve, a clutch collar feathered upon the crank shaft to move into and out of engagement with said clutch portion, a bell crank having its elbow pivoted Within the crankcase. one arm of the bell crank being operatively engaged with the clutch collar and its other arm being operatively engaged with said piston rod, said piston rod projecting toward the crank shaft, and means carried by said bracket for holding the piston rod releasably in either of two positions. In testimony that I claim the foregoing as my own, I have hereto affixed my signature in the presence of two witnesses.

GEORGE XV. DOPKINS. 

